This invention relates to a dry shaving apparatus with a housing in which an electric drive mechanism is provided having a drive element for the transmission of a driving motion to at least one reciprocating cutting element, and with at least one shaving head mounted on two support arms of a supporting frame for pivotal movement about a pivot axis within a shaving head frame, the shaving head being formed by at least two cooperating cutting elements disposed in shaving head frame.
A dry shaving apparatus of the type initially referred to is known from DE 36 10 736 C2. The shaving head frame of the shaving head including cutting elements is mounted on two support arms of a supporting frame for pivotal motion about a pivot axis Z. The pivot bearings are formed by a cylinder element which is pivotally received in a bearing bore and can be a component part of a cylindrical pin or a fastening screw.
It is an object of the present invention to improve in an apparatus of the type identified in the foregoing the bearing arrangement of a shaving head pivotal about a pivot axis. The bearing arrangement should reliably withstand any contact pressures exerted on the cutting elements during use of the dry shaving apparatus as well as any movements of the shaving head. In addition, it is desirable for the shaving head to be readily mountable on and demountable from the support arms.
According to the present invention, this object is accomplished in a dry shaving apparatus of the type initially referred to, characterized in that the shaving head is mounted and held for pivotal movement about the pivot axis by means of a conical bearing acted upon by spring force of a spring element.
According to the present invention, for a dry shaving apparatus of the type initially referred to a further solution of this object is presented by a dry shaving apparatus of the type initially referred to, characterized in that the shaving head is mounted and held for pivotal movement about the pivot axis by means of a conical bearing acted upon by spring force of a spring element and is mounted and held for oscillation in at least one other direction of movement.
Each of the two solutions referred to in the foregoing ensures a reliable, zero play mounting of shaving heads movably carried on support arms. The conical bearings acted upon by a spring force of a spring element compensate, within a predetermined range, for the contact pressures exerted on the shaving head during operation without causing separation of the components of the conical bearing including the conical bearing""s fastening elements. Any wear occurring on the components of the conical bearing during the service life of the dry shaving apparatus is compensated for automatically. Where a screwed connection is involved as, for example, in DE 36 70 732 C2 initially referred toxe2x80x94see FIG. 11xe2x80x94, it may happen that the screwed connection works loose as a result of the movement of the shaving head, a mounting screw, once worked loose, being known to be unable to return of itself to its originally tightened position. In consequence, the function of the shaving head is more or less impaired or, even worse, fails to be performed.
A further advantage derivable from the present invention resides in the utilization of a conical bearing which affords ease and economy of manufacture and ready assembly with the associated spring element in the interior of the shaving head""s shaving head frame by means of a snap-fit connection. Furthermore, the snap-fit connection provided also affords ease of demounting should this become necessary.
A preferred embodiment of the present invention is characterized in that, unlike the pivotal movements about the pivot axis, one of the other directions of movement is determined by the directions of movement of a cutting element. Being an oscillating movement, this further movement of the shaving head, which is associated with the pivotal movement of the shaving head about the pivot axis Z, is conducive to the threading of the hairs into the cutting area of cooperating cutting elements. Oscillating movements and/or pivotal movements of shaving heads present continuous loads which are balanced out by both of the aforementioned Solutions in advantageous manner.
According to a preferred embodiment of the present invention, provision is made for the conical bearing to be formed by an envelope surface of a cone and by an annular surface of a depression shaped in a conical configuration. This configuration of the conical bearing provides for distribution of the contact pressures exerted on the shaving head to the envelope surface of the cone and the annular surface of the conical depression. In a further aspect of the present invention, the depression is preferably provided in an end wall of an end cheek of the shaving head frame. In a preferred embodiment of the present invention, the depression is provided in an inner wall of an outboard end wall of the shaving head frame.
In a preferred aspect of the present invention the cone is fastened to the support arm.
In an advantageous embodiment of the present invention the spring force is producible by a spring element abutting at least one wall of the shaving head frame as well as the support arm. To provide for a particularly advantageous cooperation of the conical depression with the cone and support arm and the spring element as well, an abutment surface for the spring element is provided on the support arm on the side facing away from the cone.
In a preferred embodiment of the present invention a receiving chamber for the support arm and the spring element is provided in each end cheek of the shaving head frame. This arrangement ensures simple integration of the support arms in the shaving head frame. In consequence, the outer walls of the shaving head are free from support elements and may be used for the employment or arrangement of other devices or fixtures on the shaving head.
In another aspect of this embodiment provision is made for a respective stop for the spring element on opposed end walls of the receiving chamber.
A further advantage results according to the invention in that an opening is provided in the end wall of the end cheek. This opening can be put to a plurality of uses. For example, it may facilitate significantly the assembly and/or demounting of the snap-fit connection between the support arms and the shaving head frame in connection with the spring element, in addition to serving the function of a detent element for the spring element.
In a preferred embodiment of the present invention the spring element is constructed as a leg spring.
In a further aspect of this embodiment a detent element is provided on the spring element. Preferably the detent element is constructed as a detent arm.
For the purpose of a locally definable transmission of the spring force of the spring element to the support arm, a substantially hemispherical projection acting as pressure element is provided on the spring element. In a further aspect of the present invention the leg spring includes at least two spring legs extending towards one another in substantially triangular shape. In a further aspect of this embodiment one spring leg has two associated spring legs. In a still further aspect of this embodiment, the projection is provided on the one spring leg, and the associated spring legs are each provided with a stop nose which is arranged in a direction opposite to the projection in a manner protruding relative to the one spring leg. In this embodiment, preferably, one end of the spring leg is engageable with the stop of the end wall, while the opposite end is engageable through the stop nose with a first stop of the opposite end wall. In a preferred embodiment of the present invention, with the spring element in installed condition a distance is present between a second stop of the end wall and the stop of the spring leg. This embodiment is further characterized in that the penetration depth T of the cone into the conical depression is greater than the distance W. By suitably dimensioning the penetration depth T and the distance W it is possible to introduce the support arm into the receiving chamber until the cone snaps into the conical depression for the purpose of forming a conical bearing, thereby ensuring a reliable, secure mounting of the shaving head on the support arms once the leg spring is clipped on.
The provision of a further resilient detent arm on the leg spring which in assembled condition is biased into engagement with an opening provided in the inboard end wall where it bears against an inner wall of the opening secures the mounting of the shaving head on the support arms such that demounting of the shaving head from the support arms can only be effected by exerting deliberately a pressure on the resilient detent arm.
This type of snap-fit connection reliably withstands any stresses, strains and loads acting on the shaving head, simplifies both assembly and demounting of the shaving head and, moreover, affords low-cost manufacture.
According to an embodiment of the present invention, at least one support arm is of an elastic configuration. In a further embodiment of the present invention the elastic force is producible by pressure exerted by opposed walls of the shaving head frame on the support arms.
Further advantages and details of the present invention will become apparent from the subsequent description and the accompanying drawing illustrating a preferred embodiment of the present invention.